Drill

Abstract

A drill is disclosed. The drill includes a drill head made of hard metal and a shank made of steel to which the underside of the drill head is fastened integrally. The underside is curved inwardly in a cone-shaped manner.

1 . A drill, comprising:
 a drill head made of hard metal; and   a shank made of steel;   wherein an underside of the drill head is fastened integrally to the shank, and wherein the underside is curved inwardly in a cone-shaped manner.   
     
     
         2 . The drill according to  claim 1 , wherein the drill head is joined with the shank. 
     
     
         3 . The drill according to  claim 1 , wherein a slope of the underside deviates by less than twenty degrees from a slope of a cutting edge of the drill head. 
     
     
         4 . The drill according to  claim 1 , wherein a deviation of a thickness of the drill head in a plane through a cutting edge and an axis is less than twenty percent of an average thickness of the drill head. 
     
     
         5 . The drill according to  claim 1 , wherein a surface of the shank facing the drill head has a convex curvature. 
     
     
         6 . The drill according to  claim 5 , wherein the curvature represents at least eighty percent of a cross section of the shank. 
     
     
         7 . The drill according to  claim 1 , wherein the underside has depressions and/or elevations, wherein a height of the depressions and/or elevations is a maximum of fifteen percent of a height of the drill head. 
     
     
         8 . The drill according to  claim 7 , wherein a ratio of a width of the depressions and/or elevations to the height is between 0.5 and four. 
     
     
         9 . The drill according to  claim 7 , wherein a radius of curvature of surfaces of the depressions and/or elevations is greater than 0.1 mm in each direction.